Duck mating is an arms race

Researchers in North America are developing a novel way to study the "evolutionary arms race" that is duck mating

A duck pond may seem like the ideal place to spend a peaceful spring afternoon, but during mating season it can look like the scene of a gang attack. Though ducks as a species are famously monogamous, unattached drakes can be extremely aggressive. They attack any female in sight in a mating frenzy that often ends in the injury or death of the victim. This has resulted in the ducks developing ways to prevent unwanted matings and the drakes ways to overcome their defenses. Researchers in North America are developing a novel way to study this "evolutionary arms race" that uses high-speed cameras, force transducers and model duck oviducts made of glass.

Duck mating is not only alarming, these commonplace birds also conceal a very unusual anatomy. Duck genitalia shows a remarkable degree of variation between species with the penises of some breeds resembling a tiny string of limp pasta while others are longer than the male's entire body. Meanwhile, the female's oviducts are a maze of twists and curls. When mating occurs, the male is still flaccid and very suddenly inflates, inseminating the female in only a third of a second. Then things get really weird.

When University of Massachusetts professor Patty Brennan started her research into the biology of duck mating, she constructed silicone models of the duck's oviducts and had trained drakes mate with them. The idea was that the soft silicone rubber would not only recreate the shape of the oviduct, but also the texture and firmness However, to her astonishment, she saw the drake's penis inflate with such force that it pushed the twists and curls of the oviduct aside like a battering ram and ruptured the model.

This raised an interesting hypothesis. Because the drakes are so aggressive, the ducks were evolving defenses against unwanted mating and the males were responding with countermeasures. The females evolve oviducts that are like the gates of a medieval fortress while the males find ways to breach the defenses According to Brennan, "This is known as an evolutionary arms race. Much like the Cold war, each side escalates their armament to try to win the conflict"

To learn more, Brennan contacted biomechanics researcher Dianne Kelly who explains that a new model was needed: "When the males inflated their penises into those models, they broke them. She had to switch to model oviducts made of glass to complete the experiment." The problem was that, unlike the silicone models, the glass ones had no "give" in them, so it was harder to determine what was happening inside.
The new ones needed to be equipped with force transducers to measure the force and speed of the drakes' ejaculations while high-speed cameras would provide further information. In the next phase of the experiment, the sensor-equipped glass models will be taken to a farm in Quebec, Canada where drakes have been trained to provide sperm for artificial insemination. There tests will be carried out using the models and the results recorded in what the researchers say will be "the first detailed measurements of the physical forces generated by a penis during copulation"

This research is also notable because it is funded by a innovative means of raising money for small projects. Instead of relying on traditional grants, Brennan and Kelly are funding their work through public donations. Hosted by RocketHub, visitors to the project's website can donate and in return receive any of a number of premiums ranging from access to the project's blog up to a duck dinner with the researchers.

Whether or not the duck in question was a project participant is left undisclosed.

Researchers in North America are developing a novel way to study the "evolutionary arms race" that is duck mating

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